An exciting search engine that helps diagnose rare medical diseases, called Find Zebra

A phrase that every medical student has heard during their training is, “When you hear hoofbeats, don’t expect to see a zebra”.  This basically mean you should try to focus on the “obvious”, and not chase rare diseases if the “obvious” makes sense. In medicine, there can sometimes be a tendency to chase and diagnose rare pathology because it’s “sexy”.  We are trained against this because we can cause harm by over-testing and if your final diagnosis makes sense, and fits the overall clinical picture — then you shouldn’t go looking for a zebra.

But when you can’t find a diagnosis that fits the overall clinical picture — it can be difficult to find the zebra.  Often you have to rely on case reports on PubMed or use Google Scholar.  Finding articles using these two methods can be arduous and take a significant amount of time.

Enter Radu Dragusin and colleagues from the Technical University of Denmark, who have created the aptly titled Search Engine — “FindZebra”.  Dragusin and colleagues have indexed specially selected sets of curated databases on rare diseases, such as Orphanet, Online Mendelian Inheritance in Man (OMIM), and even sections of Wikipedia.

Below is their table 1 explaining the resources used to compile the dataset of rare diseases.



Using an open source information retrieval tool, they search this index and the result is

I used the FindZebra to look for a zebra diagnosis that was one of my favorites of Residency — Hemophagocytic lymphohistiocytosis (HLH).  Significantly elevated ferritin levels are one of the hallmarks of this rare disease, and when I typed in “high Ferritin”, I did not get HLH in the top 20 diagnoses. But when I added anemia and neutropenia (associated findings), HLH was one of the top 20 diagnoses.

This search engine is exciting.  Obviously, there is still a lot of work that needs to go into Find Zebra as it just launched, but the researchers who created this search engine should be applauded. is a novel idea and I certainly think it can be used by Physicians if they are having difficulty with a patient’s diagnosis.  The diagnoses listed by FindZebra can help Physicians expand their differentials and could help shorten the time a rare disease goes undiagnosed. 

PDF of research article on FindZebra

Source: Technology Review 


Iltifat Husain, MD

Founder, Editor-in-Chief of Assistant Professor of Emergency Medicine and Director of Mobile App curriculum at Wake Forest University School of Medicine. He is also the founder of iPrescribeApps, a platform for prescribing apps to patients. Dr. Husain has given lectures on digital medicine globally. He went to North Carolina State University for undergrad and went to medical school at Wake Forest School of Medicine.

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2 Responses to An exciting search engine that helps diagnose rare medical diseases, called Find Zebra

  1. Stuart Ray March 19, 2013 at 9:14 am #

    If you like this resource, you might like Zebra Cards (by John Sotos, former Osler house officer and consultant to the TV show House). You can order them from any bookstore. Obviously not the same as a searchable web tool, but appealing for some of the same reasons (and Zebra Cards are witty).

  2. InfoWadingROom March 19, 2013 at 10:59 am #

    Though I applaud those behind this tool and look forward to
    testing it out myself, I feel I need to point out that searching in
    PubMed and Google Scholar shouldn’t be the only alternative. For
    teaching hospitals, and most often in non-teaching hospitals, there
    should be a Medical Library and Librarian you can go to for high
    quality resources/information. It’s no longer days of dusty books
    either, we help you search high quality databases and get those
    arduous, time-consuming and hard to find articles to you asap.
    There is such a misconception that everything is avaialble or if
    not, not available at all – Medical Librarians are an amazing and
    often untapped resource/information experts for Med students,
    Physicians, Nurses – – anyone in healthcare really. We connect you
    to the most relevent up to date high quality information and let
    clinical staff get back to treating patients! Now you have emen
    more ammo to treat those patients with the best information

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